Field of the Invention
The invention concerns an items processing apparatus to place and singulation of flat items. Such apparatuses are used as, for example, modules of items processing systems or as stations of a mail processing path.
Description of the Prior Art
A mail processing path of a franking system is composed of individual mail piece processing stations arranged in sequence. A placement station serves to place single or stacked mail pieces and is situated upstream in terms of the mail flow, i.e. at the start of the mail processing path. A stack of mail pieces of different formats (mixed mail) that has been placed at the placement station is separated in the mail processing path by an separation device of a feed station (this separation device immediately following in the transport direction) since additional following mail piece processing stations require singularly supplied mail pieces. The placement and separation stations of the mail processing apparatus, or specifically the items processing apparatus for placement and separation of flat items, are provided for use in connection with subsequent items processing devices, for example in connection with franking machines, addressing machines and other printing mail processing apparatuses.
As used herein, “mixed mail” means mail pieces of similar format that differ by up to 10% in height and width, within limits, for example letters of formats B6 (12.5×17.6 cm) and C6 (11.4×16.2 cm).
When a “stack” is discussed in the following, this means letter stacks, postcard stacks and other mail piece stacks or a different stacked item that can be separated.
In the field of franking machines, mechanisms are known that transport a mail piece downstream (in terms of the mail flow) in the transport direction, and print the mail piece with a franking imprint during the transport.
In the Centormail® franking machine that is commercially available from Francotyp-Postalia GmbH and Francotyp Postalia USA, such mixed mail is transported by means of a transport belt while standing on edge, wherein an alignment of the mail pieces by gravity automatically takes place at the edge.
In the field of franking machines, solutions are also known—for example the PostBase® franking machine that is also commercially available from the above sources—that transport a mail piece resting on its side downstream (in terms of the mail flow) in the transport direction. An automatic feed station may precede the franking machine at the mail intake side. A modular placement device of a feed station has been described in German utility patent DE 20 2011 107 379 U1 (U.S. Pat. No. 8,702,090 B2). The feed station follows downstream (in terms of the mail flow) of a placement station. The latter is designed as a purely manually operable module without its own drive engineering, the placement deck of which may be set up like a ramp as needed. Due to the ramp design in such a manner, gravity is used to assist in the supply of mail pieces. However, no alignment of the mail pieces takes place due to gravity. Rather, a slide is provided with which a stack is manually pressed onto a guide plate of the placement station, this guide plate serving as an alignment wall. However, it cannot be ensured with this design that all mail pieces of a mixed mail stack will rest with their side edge against the alignment wall. This edge alignment uncertainty is problematic when the mail pieces transported lying on their side should be aligned at an alignment, placement or guide wall without the assistance of gravity.
Known mail processing apparatuses supply the lowermost mail piece of a mail piece stack to the alignment wall by driven rollers. A feed station for a mail handling machine that is provided to handle mixed mail (filled envelopes with open or closed envelope flap) at high speed is known from U.S. Pat. No. 4,973,037. This is equipped with a stack plate, a device for transverse movement of a side wall relative to the stack plate, and transport devices in a stack magazine region. A portion of the transport devices is situated below the stack plate. The side wall serves as an alignment surface against which the flap edges of envelopes may be brought to a stop.
Means are provided for transporting the mail pieces both downstream and in the direction toward the alignment wall, as well as to loosen the mail pieces (open or closed, filled letter envelopes) of a stack so that they may slide over one another more easily. These transport means are eccentrically designed loosening rollers with different coefficients of friction. Roller groups are driven by a motor and move back and forth periodically in a small angle range by means of a disc cam. Moreover, a repeated inclined positioning of the mail stack plate in the stack magazine region is proposed in order to utilize the force of gravity for the alignment of the mail pieces. Upon transitioning into the supply region, due to the repeated inclined positioning of the mail stack plate in the stack magazine region the letter envelope may possibly also be horizontally pinched, in particular given an open envelope flap. An alignment of the mail pieces is possible only to a limited degree via the small angle range. Moreover, the placement cover is large relative to the largest format of a mail piece, such that small dimensions of the base of the mail processing apparatus cannot be achieved.
Moreover, an alignment can be achieved only as long as the letter envelope has not reached the separation gate. As soon as the letter envelope rests at the gate entrance, it is drawn into the separation gate. A displacement of the stack and its alignment at the alignment or placement wall is then no longer possible. Means to loosen a stack of mail pieces are used in order to reduce the stiction between the mail pieces, which enables an alignment of the stack at the alignment wall before the separation of the mail pieces. The means for loosening a stack of mail pieces (letters) are, however, ineffective when multiple mail pieces (letters) have already been driven into the separation gate. Consequently, it must either be prevented that multiple mail pieces (letters) are driven into the separation gate, or the status must be retroactively corrected. An advantage of the separation of the respective lowermost mail piece is to provide the possibility of refilling additional mail pieces from above onto the stack, which is possible without interrupting the operation of the separation device. However, the weight of the stack is thereby increased, and thus the stiction is also increased between the lowermost mail piece and the respective following mail piece that is to be separated. That in turn leads to the situation that a number of thin mail pieces (letters) is increasingly drawn into the separation gate.
Given a mixed mail stack with a few thick mail pieces (letters), a hard-set separation gap cannot be used; rather, the mail pieces (letters) push the separation gate apart depending on their thickness. Letters may remain stuck to one another not only due to the stiction but also due to electrostatic charge. More than one letter may thus be driven into the separation gate simultaneously, which occurs increasingly given thin letters of the mixed mail stack, and causes unwanted malfunctioning. An additional problematic state occurs in a separation device in the event that, after each removal of the respective lowermost letter of the stack, the subsequent letters are always drawn further into the gate than the respective preceding letter before the subsequent letter. In order to minimize these malfunctions, such gates are preset to a required thickness range. That in turn limits the mixed mail capability of the separation device.
A feed station is known from German utility patent DE 20 2012 011 876 U1. The feed station has a pre-separation region, a separation region and a transport region. The transport region is arranged along a transport path, after the separation region in the transport direction. A processor of a control computer of the feed station is programmed to reduce the gap between the individualized flat items to a desired clearance through a corresponding control of transport rollers. The transport rollers are arranged in the transport region. The separation region lets through letters with a maximum thickness of 10 mm. The throughput of the separated letters is limited to 65 letters per minute.
In German utility patent DE 20 2012 011 877 U1 (U.S. Pat. No. 8,965,568 B2), a feed station is disclosed to supply a flat item that rests lying on its side at a placement station and is singulated or is separated from a stack and transported downstream by means of the feed station in order to supply the item to a subsequent items processing apparatus. A control computer has a processor, a signal processing means for the signals of the sensors and the encoders, and a determination unit to determine the position of the flat item. The processor of the control computer is programmed to increase a gap between the separated flat items to a desired clearance. According to DE 20 2012 011 877 U1, the stack is situated with the respective lowermost flat item partially on a first separation roller, which is arranged in the pre-separation region of the feed station. A second separation roller is arranged at a clearance from this (in the transport direction) in the separation region of the feed station.
A contact pressure box that can be vertically displaced for maintenance purposes is installed at a frame of the feed station. The contact pressure box has two contact pressure rollers charged with elastic force, wherein the elastic force is exerted by compression springs. The compression springs are supported inside the contact pressure box. The contact pressure box is mounted in the frame so as to be lockable. The two contact pressure rollers press with an elastic force on two transport rollers whose rotation axis shafts are borne under the cover, on the frame of the feed station, and which respectively protrude upward in the transport region through separate openings in the cover of the feed station. During the transport, a flat item is pinched by the two pairs of contact pressure rollers-transport rollers and transported further along the transport path. The contact pressure roller has a pivotable linkage, which charged with elastic force by a tension spring—exerts a contact pressure force via multiple separation fingers on a flat item to be singulated in the separation region of the feed station, which flat item enters into a gap between a second separation roller and the separation fingers as a result of the driving of the transport elements of the placement station. Measures which should prevent the entrance of multiple thin, flat items into the gap (DE 20 2012 011 877 U) have been taken before and above the gap. The separation device of the feed station has a gate for flat items that is formed in multiple stages in the separation region and comprises at least one pre-gate and a main gate. A stack of flat items on the feed deck rests on the mail intake-side wall of a housing part of the feed station. The lower edge of the housing part forms a first stage that is situated approximately 30 mm above and in parallel with the surface of the feed deck. The first separation roller projects approximately 6.5 mm beyond the surface of the feed deck. This first stage holds back the flat items as of a stack height of greater than 23.5 mm. A stack stop surface with stepped, angled plate at the lower edge of a pre-separation region forms a second stage of holding back the stacked flat items of the stack. The latter is installed at the head end of the linkage. A majority of the shaped body of the linkage, which forms a long lever arm in the transport direction, is situated between the head end of the linkage and the rotation point of the rotatably borne linkage. The lower side of the step of the inclined angle plate is situated approximately 18.5 mm above the surface of the feed deck, for example. As a result of this, only a single, thick, flat item with a maximum thickness of 12 mm, or multiple thinner flat items, may pass this step. Following after the aforementioned step are the pre-separation fingers attached above at the head end of the linkage and pointing angled downward in the transport direction, and following downstream is a ramp plate (likewise arranged inclined) to which the separation fingers are attached. The latter, together with the second separation roller, forms the main gate. Although the separation region is formed in multiple stages, according to DE 20 2012 011 877 U1 this design is not suitable for all flat items; rather, it was developed for mail pieces in particular.